Jastrzebski Nicola R, Hugrass Laila E, Crewther Sheila G, Crewther David P
Centre for Human Psychopharmacology, Faculty of Health, Arts and Design, Swinburne University of Technology Hawthorn, VIC, Australia.
School of Psychological Sciences, La Trobe University Bundoora, VIC, Australia.
Front Integr Neurosci. 2017 Mar 16;11:7. doi: 10.3389/fnint.2017.00007. eCollection 2017.
Visual estimation of numerosity involves the discrimination of magnitude between two distributions or perceptual sets that vary in number of elements. How performance on such estimation depends on peripheral sensory stimulation is unclear, even in typically developing adults. Here, we varied the central and surround contrast of stimuli that comprised a visual estimation task in order to determine whether mechanisms involved with the removal of unessential visual input functionally contributes toward number acuity. The visual estimation judgments of typically developed adults were significantly impaired for high but not low contrast surround stimulus conditions. The center and surround contrasts of the stimuli also differentially affected the accuracy of numerosity estimation depending on whether fewer or more dots were presented. Remarkably, observers demonstrated the highest mean percentage accuracy across stimulus conditions in the discrimination of more elements when the surround contrast was low and the background luminance of the central region containing the elements was dark (black center). Conversely, accuracy was severely impaired during the discrimination of fewer elements when the surround contrast was high and the background luminance of the central region was mid level (gray center). These findings suggest that estimation ability is functionally related to the quality of low-order filtration of unessential visual information. These surround masking results may help understanding of the poor visual estimation ability commonly observed in developmental dyscalculia.
数字的视觉估计涉及对两个在元素数量上不同的分布或感知集合之间大小的辨别。即使在发育正常的成年人中，这种估计的表现如何依赖于外周感觉刺激仍不清楚。在这里，我们改变了构成视觉估计任务的刺激的中央和周边对比度，以确定与去除不必要视觉输入相关的机制是否在功能上有助于数字敏锐度。对于高对比度但非低对比度的周边刺激条件，发育正常的成年人的视觉估计判断明显受损。刺激的中央和周边对比度还根据呈现的点的数量较少还是较多而对数字估计的准确性产生不同影响。值得注意的是，当周边对比度低且包含元素的中央区域的背景亮度暗（黑色中心）时，观察者在辨别更多元素的刺激条件下表现出最高的平均准确率。相反，当周边对比度高且中央区域的背景亮度为中等水平（灰色中心）时，在辨别较少元素的过程中准确性严重受损。这些发现表明，估计能力在功能上与非必要视觉信息的低阶过滤质量相关。这些周边掩蔽结果可能有助于理解在发育性计算障碍中常见的较差视觉估计能力。
